Abstract

We describe a quartz crystal microbalance setup that can be operated at low temperatures in ultra high vacuum with goldelectrodesurfaces acting as substrate surface for helium diffraction measurements. By simultaneous measurement of helium specular reflection intensity from the electrodesurface and resonance frequency shift of the crystal during filmadsorption, helium diffraction data can be correlated to film thickness. In addition, effects of interfacial viscosity on the helium diffraction pattern could be observed. To this end, first, flat goldfilms on AT cut quartz crystals were prepared which yield high enough helium specular reflection intensity. Then the crystals were mounted in the helium diffractometersample holder and driven by means of a frequency modulation driving setup. Different crystal geometries were tested to obtain the best quality factor and preliminary measurements were performed on Kr films on goldsurfaces. While the crystal structure and coverage of krypton films as a function of substrate temperature could successfully be determined, no depinning effects could be observed.

Received 19 August 2011Accepted 16 October 2011Published online 09 November 2011

Acknowledgments:

This work was partially supported by TUBITAK Grant Nos. 107T408 and 209T084. We thank Giacinto Scoles and Gianangelo Bracco for fruitful discussion and technical help with this work. We thank Mustafa Kulakçı, Raşit Turan, and Mehmet Parlak for their help with the use of thermal evaporator.